@article{AUCMP_2009_50_1_a5,
     author = {Trch, Milan},
     title = {Groupoids and the associative law {IIIA.} {(Primitive} extensions of {SH-groupoids} and their semigroup distances)},
     journal = {Acta Universitatis Carolinae. Mathematica et Physica},
     pages = {73--82},
     year = {2009},
     volume = {50},
     number = {1},
     mrnumber = {2569470},
     zbl = {1181.20062},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUCMP_2009_50_1_a5/}
}